Koi (specifically Yamabuki Ogon variety)
Cyprinus rubrofuscus
Type: Freshwater, Benthic
Physical Characteristics
Elongated, torpedo-shaped body with a metallic yellow or gold coloration known as 'Yamabuki'. It features prominent scales, a single dorsal fin, and two pairs of barbels near the mouth. This specimen exhibits a solid metallic sheen without additional patterns.
Habitat & Distribution
Native to Central Asia but widely distributed globally in ornamental ponds, gardens, and lakes. They prefer slow-moving or stagnant freshwater with soft sediment bottoms.
Size & Weight
Typically ranges from 24 to 36 inches (60–90 cm) in length, though they can reach up to 3 feet. Large specimens can weigh between 10 to 35 pounds depending on environmental conditions.
Similar Looking Species
Common Carp (Cyprinus carpio), which lacks the bright metallic colors; Goldfish (Carassius auratus), which lack barbels and typically do not grow as large.
Ecological Role
As bottom-feeders, they stir up sediment (bioturbation), which can increase water turbidity. In non-native environments, they can become invasive by out-competing local species and altering aquatic vegetation levels.
Diet
Omnivorous and opportunistic feeder. Diet includes algae, aquatic insects, worms, crustaceans, and plant matter. They use their sensitive barbels to find food in the substrate.
Behavior
Social and schooling fish that are generally docile. They are most active during the day (diurnal) and exhibit higher activity levels in warmer water. They are known for their ability to recognize frequent visitors.
Reproduction
External fertilizers that spawn in spring or early summer when water temperatures rise. Females scatter thousands of adhesive eggs over aquatic vegetation, which the males then fertilize.
Conservation Status
Vulnerable (The wild ancestor Cyprinus rubrofuscus is listed as Vulnerable by the IUCN, though domesticated koi are abundant).
Identification Tips
Look for the metallic yellow 'Yamabuki' color and the presence of sensory barbels (whiskers) at the corners of the mouth, which distinguishes them from giant goldfish.
Interesting Facts
Koi are symbols of luck, prosperity, and perseverance in many East Asian cultures. Some individual koi have been known to live for over 50 years, and they are capable of being trained to eat from a hand.
Identified on: 4/25/2026
Mode: Standard